By Bruce Tews
I do not like leaks of any kind, whether they be engine oil, transaxle oil, or gas, and maybe, especially gas. So, my Zenith carbs leaked, and I was not going to tolerate the leaks. Mine no longer leak, and this is how I fixed them.
First, get yourself a mirror. Mirrors are extremely flat. A one foot by one foot mirror panel from Home Depot or Lowe's is perfect. Also get some JB Weld and liquid teflon in a tube. (More on these later). Tape the edges of the mirror to a flat place, maybe the countertop next to your kitchen sink because you need water for the emery cloth which you will use. Then, if you are up to it, take your Zenith sections apart and do what Ron and others suggest, which is, tape a piece of 300 to 400 grit emery cloth on the mirror and resurface the flat sections of the carbs.
Second, follow their other instructions regarding float levels, etc, including not removing the screw within a screw under the middle carb section.
Third, follow my instructions. Get rebuild kits from Al Zim or wherever. As Ron points out regarding burrs on some crush washers in rebuild kits, use the mirror with fine grit emery cloth to polish the crush washers. Get good at doing this, and you will be very happy!
Clean the carbs with whatever you desire, but make sure all pieces are very clean and dry. DO NOT put anything on the new gaskets. Dry gaskets are what you want!
Find yourself some copper crush washers that will nicely fit every external screw in your Zeniths other than the ones which hold them together. I am talking about screws on your Zeniths which never had crush washers before. These need to be made by you. I actually made some from copper washers that were a very good outside diameter, but I needed to punch out the inside diameter to be a good fit. To make these, I used a hand held punch from Harbor Freight Tools, and used a piece of masking tape to hold and center the copper washer within the punch. Anyway, use the mirror and polish the surfaces of the newly made crush washers. Then, get some liquid teflon in a tube, and place a small amount on both sides of every crush washer before assembling them on the carbs.
Now, I am probably going to get some barbs thrown at me for this, but this was the final fix for my Zenith leaks. I must tell you that I had to take them off the car around 9 times before I finally got them leak less. There are a few aluminum (I think) plugs in the carbs, two or three on each carb. (Mine have not leaked for a long time so I do not remember). When you have the carbs nicely clean and dry, lay them on their sides and prop them up with something such that the little plugs are facing upwards and very horizontal. Take the JB Weld that you purchased and mix some up. Take a toothpick, pick up a little of the mixed JB Weld, and put a nice little drop onto each aluminum plug so the drop extends a bit over each plug and onto the nice patina of the pot metal. I am aware that some folks say the plugs never leak, but mine did, and it was the final fix for all my leaks. [Ken Daugherty adds, "On the plugs, you can accomplish the same thing with no appearance change with a drop of wicking locktite at the edge of each one."]
Now et the carbs rest for 24 hours. Install them, start the engine, look for leaks for a few days, and do whatever it takes to find and fix any more leaks. This is what is called a reiterative process, but you will succeed. I have!